Radiotherapy Analysis
Radiotherapy verification can be defined as “the process by which the accuracy of radiotherapy is assessed. It is achieved by comparing images (or data) of the treatment delivered with that planned.” (Royal College of Radiologists, 2008, p10).
Greater contrast occurs between bone and soft tissue when using kilovoltage imaging such as OBI compared to megavoltage imaging such as EPI, for verification. As kV images are produced photoelectric absorption occurs, “the probability of the interaction…is approximately proportional to Z [atomic number] cubed.” (Cooke, 2009, p40). According to Cooke (2009) as bone has a greater atomic number than soft tissue, the absorption of radiation in bone is much greater, this causes a large contrast between these two mediums in the kV image. As mV images are produced Crompton scatter occurs. Cooke (2009) states that it is independent of atomic number and dependent on the density of the medium, the difference in density is small between bone and soft tissue, consequently there is a small difference between the radiation absorbed between them. This produces a lesser contrast compared to kV imaging between these two mediums.
During the VERT session, I decided upon critical match points for anterior and right lateral EPI images. Recorded …show more content…
On-line imaging protocols may be used for numerous days which is dependent on individual departments. According to Holborn (2009) they are used for patients beginning a course of treatment as it is advantageous, the protocol “establishes accuracy and reproducibility”. (Conway and Johnson, 2012, p156). Holborn (2009) states that images are taken following patient set up and assessed prior to treatment on the same day, action is taken to move the patient if it is shown they were incorrectly
Greater contrast occurs between bone and soft tissue when using kilovoltage imaging such as OBI compared to megavoltage imaging such as EPI, for verification. As kV images are produced photoelectric absorption occurs, “the probability of the interaction…is approximately proportional to Z [atomic number] cubed.” (Cooke, 2009, p40). According to Cooke (2009) as bone has a greater atomic number than soft tissue, the absorption of radiation in bone is much greater, this causes a large contrast between these two mediums in the kV image. As mV images are produced Crompton scatter occurs. Cooke (2009) states that it is independent of atomic number and dependent on the density of the medium, the difference in density is small between bone and soft tissue, consequently there is a small difference between the radiation absorbed between them. This produces a lesser contrast compared to kV imaging between these two mediums.
During the VERT session, I decided upon critical match points for anterior and right lateral EPI images. Recorded …show more content…
On-line imaging protocols may be used for numerous days which is dependent on individual departments. According to Holborn (2009) they are used for patients beginning a course of treatment as it is advantageous, the protocol “establishes accuracy and reproducibility”. (Conway and Johnson, 2012, p156). Holborn (2009) states that images are taken following patient set up and assessed prior to treatment on the same day, action is taken to move the patient if it is shown they were incorrectly